Racial studies could provide useful information, not only in terms of genetic predisposition to acne but also regarding the role of environmental factors, such as diet and ultraviolet light. Regrettably, few satisfactory racial studies of acne have  been published.  Acne in black Americans is less evident than in white Americans who, in turn, have more severe acne than Japanese in Tokyo and Yokohama.18 The age incidence curves for Americans are similar  to  those of males and females  in Switzerland. These observations, and the reported higher incidence of male pattern baldness in Caucasians than in Mongoloids, are  in accord with the idea  that tendencies  to pronounced development of secondary sex characteristics may merge with tendencies to certain sex-selective pathological  conditions.